Macro Lens alignment for maximum sharpness ??

[Stagecoach]

I was browsing through a photography book of mine today and came across the statement, in two places referring to macro, that to achieve maximum sharpness the lens should be positioned exactly horizontal.

It does not suggest at all that the reasoning is to get the camera on the plane that is going to get the most from the limited DOF. E.G. having your lens aligned with the head and tail when shooting a dragon fly from on top which is what most of us would try to achieve.

I'm confused by this and can not think of a reason why, can anyone enlighten me?

Grahame

[FrankMi]

Hi Grahame, if no reason suggestion is being made along with this statement, perhaps one is assumed by text presented elsewhere in the document? Logically, the reasons you have presented are valid.

[chauncey]

Grahame...you forced me to do this and I'm still totally confused by the outcome.
Crossword puzzle shot horizontally, then at a 45 degree angle.





I don't understand why the "in-focus bar" doesn't always remain on a horizontal axis regardless of the rotation of the camera, especially when the camera is rotated to 90 degrees, that bar is again horizontal. It's the same as rotating the image in PP???

[Black Pearl]

Would the books author be referring to copy work where it would be beneficially to keep everything aligned?
If there is talk of 'Flat Field' then this could the case.

[Stagecoach]

Ok, here is the paragraph from the book;

Quote, Macro lenses have a "sweet spot" where you get absolutely the most sharp results, and in macro photography, having tack-sharp images is critical. One trick to get the most sharpness out of your macro lens is to shoot with your lens aiming perfectly straight at the subject (in other words, don't angle your lens upward or downward toward your subject - try to shoot straight on for the best sharpness and clarity). So, for example, if you're shooting a bee on a flower, you'll need to lower your tripod to the point where you are aiming directly at the flower without having to tilt the lens, even a little bit (as shown above). Unquote.

The picture above this shows a single flower (coincidentally the same as Chauncey is shooting at present) in a glass vase with the stem roughly vertical so the flower petals are on the horizontal plane almost. The camera is shown on the tripod, horizontal (eg it's sensor/lens axis parallel to the table top).

The book is one by Scott Kelby whose material I find very good, hence making me think twice about this. The fact that 'sweet spot', 'tack-sharp' and 'clarity' are all used emphasises my query, I think. This chapter in the book (of which the above is all within it) is actually titled 'Maximize your depth of field', but if the above is supposed to be referring to DOF I find it rather confusing.

Grahame

[ajohnw]

I think he may be considering sagittal and tangential focal planes. Something often not clearly understood. The section on astigmatism here shows what is going on and the effect is unavoidable which is why MTF plots always show curves for both. There is a sort of sweet spot in the centre of both image planes. Good luck in finding it!

http://www.optics4kids.org/home/cont...n/aberrations/

John
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[tao2]

Ah think it's simply his use of English. Had he said "perpendicular to" instead of "horizontal"....

[ajohnw]

I think he may be considering sagittal and tangential focal planes. Something often not clearly understood. The section on astigmatism here shows what is going on and the effect is more or less unavoidable which is why MTF plots always show curves for both. There is a sort of sweet spot in the centre of both image planes. Good luck in finding it!

http://www.optics4kids.org/home/cont...n/aberrations/

John
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[DanK]

no offense to Kelby, but I think it is nonsense as written, although he might have had something more sensible in mind. Straight or tilted relative to what? To which part or surface of the bee? What difference would 'the same height as the bee' make?

AFAIK--and I do a lot of macro work--the key in choosing an angle in macro work is depth of field. You need to have the sensor close to parallel to whatever you want in focus.

[Inkanyezi]

I beg to differ...

[ajohnw]

I beg to differ...

That is a tilt shift lens set up Urban. Not really appropriate to normal macro lenses.

i Suspect that the man mean keeping the sensor plain square to what ever really needs to be in focus. He's correct about sweet spots aperture wises. Trouble is these are often at wider apertures than can effectively be used for macro work.

If you want to find out more about the practice of focusing view camaras there is plenty around here - including the problems with the method outlined in the page you have photographed. If you find the book links they can now be downloaded for free.

http://www.trenholm.org/hmmerk/HMbook11.html

John
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[Stagecoach]

Hi Grahame, if no reason suggestion is being made along with this statement, perhaps one is assumed by text presented elsewhere in the document? Logically, the reasons you have presented are valid.

Hi Frank, I can’t find anything elsewhere in the book that gives a clue as to background info for this comment. Scott Kelby does not go into technical reasons in any depth in the books of his I have which to be honest suits me fine.

Grahame...you forced me to do this and I'm still totally confused by the outcome.
I don't understand why the "in-focus bar" doesn't always remain on a horizontal axis regardless of the rotation of the camera, especially when the camera is rotated to 90 degrees, that bar is again horizontal. It's the same as rotating the image in PP???

William I am not sure this equates to the comment in question but I’m sure there’s a logical reason for what you have found so I’m just gonna try that tonight.

Would the books author be referring to copy work where it would be beneficially to keep everything aligned?
If there is talk of 'Flat Field' then this could the case.

I see what you are saying Robin but he’s referring to shooting bees and flowers.

I think he may be considering sagittal and tangential focal planes. Something often not clearly understood. The section on astigmatism here shows what is going on and the effect is unavoidable which is why MTF plots always show curves for both. There is a sort of sweet spot in the centre of both image planes. Good luck in finding it!
http://www.optics4kids.org/home/cont...n/aberrations/
John-

I had a read up on this John, a bit confused still and will study it more.

Ah think it's simply his use of English. Had he said "perpendicular to" instead of "horizontal"....

It may very well be Boab.

no offense to Kelby, but I think it is nonsense as written, although he might have had something more sensible in mind. Straight or tilted relative to what? To which part or surface of the bee? What difference would 'the same height as the bee' make?
AFAIK--and I do a lot of macro work--the key in choosing an angle in macro work is depth of field. You need to have the sensor close to parallel to whatever you want in focus.

Fully agree with you ‘key’ in choosing the shooting angle which for me will totally depend upon framing and how I want the DOF distributed.
If we simplify a bee to a sphere, what difference in anything is there going to be from whatever angle I shoot it assuming I always keep it central in the frame?

[DanK]

If we simplify a bee to a sphere, what difference in anything is there going to be from whatever angle I shoot it assuming I always keep it central in the frame?

Exactly. Kelby is just wrong, or he worded it so badly that one can't see what he meant. consider this:

So, for example, if you're shooting a bee on a flower, you'll need to lower your tripod to the point where you are aiming directly at the flower without having to tilt the lens, even a little bit

The optics don't know whether you are "tilting." and "tilting" relative to what? Relative to the ground? if you have a bee on a twig, and you make yourself exactly parallel to the bee and then rotate around the bee (hard to do, but hypothetically), you would get exactly the same portion of the bee in focus.

My advice is to forget about it. Trust me: what you have to worry about is getting the sensor parallel to what you want in focus. If that requires "tilting", relative to whatever, tilt away. for example:

close to parallel:



Not close to parallel (this is a deerfly about to bite me through my supplex hiking pants, so I didn't take the time to 'tilt' enough to make the sensor parallel):